The fibroblast growth factor-2 arrests Mycobacterium avium sp. paratuberculosis growth and immunomodulates host response in macrophages

Summary Mycobacterium tuberculosisis ( M. tb ) epidemic is one of the most severe health problem worldwide, while mechanisms underlying its pathogenesis and host immune responses remain unclear. Mycobacterium avium ( M. avium ), a mycobacterial species related to M. tb , shares similarities with M. tb in many ways. In this study, using M. avium infection of macrophages as a model, we systematically studied the effect of fibroblast growth factor-2 (FGF-2) on M. avium infection of macrophages. Our results showed that M. avium infection could increase FGF-2 expression on both mRNA and protein levels. M. avium infection elevated TNF-α and IFN-γ production while the addition of FGF-2 could further increase TNF-α but not IFN-γ level. M. avium infection could increase the expression of oxygen/nitrogen metabolism proteins iNOS and SOD-1, and FGF-2 had additive effect on the expression of these two proteins. M. avium infection had inhibitive effect on actin expression while FGF-2 could partly counteract such inhibition. Moreover, FGF-2 could inhibit M. avium proliferation in macrophages. Our results together indicate that macrophage-secreted FGF-2 upon M. avium infection could suppress M. avium proliferation through various ways including cytokine production, enhancement of phagocytosis as well as oxygen/nitrogen metabolism.